The objectives of the Registry of Experimental Cancers are the storage and retrieval of pathologic material and data on cancers and other lesions of laboratory animals (primarily rodents) and the use of such information for research and educational purposes. The Registry has acquired a total of 3,345 (476 since the 1985 report) single or group accessions from investigators outside the NCI and approximately 63,076 records have been coded. Forty-two investigators have come to the Registry for study and consultation on single or multiple visits.